06143930 is referenced by 163 patents and cites 21 patents.

Disclosed is a method to manufacture high purity acetic acid. Although described in relation to that produced by a low water carbonylation process the present invention is applicable to other mechanisms for production of acetic acid which results in formation of permanganate reducing compounds such as acetaldehyde, propionic acid, and alkyl iodide impurities in intermediate process streams. It has been found that permanganate reducing compounds and alkyl iodides may be conveniently removed from a light phase of an intermediate stream in the reaction process by employing a multiple distillation process coupled with an optional extraction of acetaldehyde. The distillation process involves first distilling a light phase to concentrate the permanganate reducing compounds, and in particular the acetaldehyde, and then separating the permanganate reducing compounds and alkyl iodides in a second distillation tower. The second distillation serves to remove the permanganate reducing compounds and alkyl iodides from methyl iodide, methyl acetate, and methanol mixture. As an optional third step, the twice distilled stream may be directed to an extractor to remove any remaining quantities of methyl iodide from the aqueous acetaldehyde stream to obtain acetic acid as a final product in greater than 99% purity.

It has been found that this process removes at least 50% of the permanganate reducing compounds and alkyl iodides and at least 20% of the propionic acid impurity from the intermediate light phase stream, and results in lower alkyl iodide concentration in the carbonylation reaction process, and in particular in the carbonylation reactor.

It has also been found that during shut down of the inventive process, polymers of acetaldehyde tend to form in the base of the second distillation tower. To avoid or minimize the formation of these polymers, a constant flow of solvent is passed through the base of the column.

Title
Removal of permanganate reducing compounds and alkyl iodides from a carbonylation process stream
Application Number
735361
Publication Number
6143930
Application Date
October 17, 1997
Publication Date
November 7, 2000
Inventor
R Jay Warner
Corpus Christi
TX, US
Richard F Vogel Jr
League City
TX, US
G Paull Torrence
Corpus Christi
TX, US
Robin Suzanne Tanke
Corpus Christi
TX, US
Mark O Scates
Friendswood
TX, US
Valerie Santillan
Houston
TX, US
Wayne David Picard
Houston
TX, US
Melchior A Meilchen
Koenigstein
DE
Michael L Karnilaw
Houston
TX, US
George A Blay
Corpus Christi
TX, US
Madan Singh
Corpus Christi
TX, US
Agent
Susan Spiering
Assignee
Celanese International
TX, US
IPC
C07C 67/36
C07C 51/12
C07C 51/42
View Original Source